Species Focus - Grass Snake (Natrix helvetica)

We haven’t seen much sunshine this spring but on warm, even overcast days, you might see Grass Snakes out and about. One of two native snake species to occur in Wales, Grass Snakes are an active species that might be seen basking and swimming in garden ponds, lakes and canals.

The Grass Snake is a harmless, non-venomous species that mostly feeds on amphibians and sometimes fish. At this time of year the females might be seen around heaps of rotting vegetation (including large garden compost and manure heaps), which make excellent egg-incubators. Grass Snake eggs hatch into miniature versions of the adults in the late summer.

Grass Snakes are easy to recognise by the yellow collar behind the head, a large eye with a round pupil and their olive-brown colour with narrow dark bars on the lower sides. Our native Grass Snakes do not have a continuous dark dorsal stripe. Most adults measure 60-70 cm, but large females can grow to over 1 metre.

The other native snake species in Wales is the Adder (Vipera berus). The Adder has a dark and distinct zigzag pattern down its back and small red eyes. Adders do not have a yellow collar. Females are brown with a dark brown zigzag and males silvery-grey or greyish brown with a black zigzag. Adders are rarely seen swimming and generally avoid gardens, unless they border directly on heathland, fenland or coastal vegetation.

Slow-worms (Anguis fragilis) are actually lizards but have been mistaken for snakes because they lack legs. Slow-worms have stocky bodies with a shiny, metallic brown, sometimes coppery colour. The head is narrow and rigid, with small eyes and a poorly-defined neck. Females have dark sides and juveniles are strikingly gold and black.

Further information on our native reptiles and amphibians is available from The Amphibian and Reptile Conservation (ARC) Trust website.

Please submit your records, ideally with photos, to the Cofnod ORS or the LERC Wales App.

Wildlife garden tips: Large, warm compost and manure heaps provide important egg-laying habitat for Grass Snakes. You can help Grass Snakes by providing an undisturbed compost heap and avoid turning over any compost/manure heaps in the summer/early autumn months. A garden pond will ensure a supply of food and water.